Does Epsom Salt Affect the Growth of Plants?

Epsom salt is a granular compound of magnesium sulfate that can be used to fertilize plants. Reports of its effectiveness vary from person to person, as well as from test to test.

Function

Magnesium sulfate adds magnesium and sulfur to soil without changing the soil's pH. Plants need both for production of chlorophyll and absorption of nutrients. Magnesium also helps grow strong roots.

Common Uses

Epsom salt is used on vegetable plants, as well as on stressed plants. Use a foliar spray to prevent or cure black-spot disease on roses. A pinch of it in the planting holes of bulbs may discourage squirrels from bothering the bulbs.

Positive Effects

The growth of plants with magnesium deficiency improves after an application of Epsom salt. Magnesium in Epsom salt drenches displaces excess sodium and leaches it out of soil in plant containers.

Negative Effects

Epsom salt does not improve growth of plants unless they are deficient in magnesium. Any results are short-lived because of the extreme solubility of Epsom salt. It may cause leaf scorch, if used as a foliar spray.

Considerations

Test soil before using any fertilizer. Local county extension offices conduct soil tests for a small fee or free, or you can choose a soil testing laboratory.

References

• North Carolina State University Extension
• Michigan State University

Resources

• WSU Puyallup Research and Extension Center
• Auburn University Extension
• Epsom Salt Council